<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let arr = [1, 2, 3, 0, 0, 0, 0];
        class P {
            constructor(arr) {
                arr.splice(3,4)
            };
            fn() {
                console.log(arr);
            }
        }
        let p = new P(arr);
        p.fn();
    </script>
</body>

</html>